1. Field of the Invention
The present invention relates generally to an image processing, more specifically to improving reliability for security of an image processing apparatus having job-lock function.
2. Description of the Related Art
In order to prevent a special original document or a secret document from being copied by a copying machine, various apparatuses and methods have been proposed.
Starting from a method of discriminating special original documents such as bank bill and paper money from imitations thereof, in an office of a company, from a viewpoint of criticality of the content or security protection of a document, there are many documents inhibited to be copied (hereinafter, referred to as “job-locked”), even for common documents other than the special original documents. In general, on such a copying inhibited document, a mark so called “secret document mark” or “copying inhibition mark” is stamped, or a specific tint pattern is printed. By extracting the stamp mark or the tint pattern from a scanned image of the original document so as to utilize it as control information, the copying inhibited document is discriminated from documents allowed to be copied. Further, a method for inhibiting copying by burying a stamp mark of “secret document” etc. or a specific tint pattern so as to detect it, is proposed. In such a technology, since it is necessary for the copying protection pattern to be buried into an output image correctly so as to be recognized, in order to improve recognition rate or accuracy or accuracy, it is required to scan an area as large as possible.
On the other hand, in many multiple-function composite machines, since, during reading, priority is given to performance depending on the size of an original document, the size of a recording paper, or a set scaling factor, in general, they are designed so as to scan a minimum necessary area of the original document. Further, in the composite machines, there is also a function to edit an image by digital processing, represented by trimming, and even in such a case, in general, a portion of the original document, which is unnecessary for formation of the image printed on a recording paper, is not scanned.
As a prior art document of the present invention, Japanese Patent Laid Open No. H07-036317(1995) is included.
If the minimum necessary area is scanned depending on an output result, the sampling area for recognizing the above-mentioned copying protection pattern will also be narrow, thus, preventing the recognition rate or accuracy from improving.
Further, in an output device such as a printer, a phenomenon may occur, in which, due to depletion of ink, or wastage of a head or a dram, degradation of print quality such as density unevenness (hereinafter, referred to as in-plane unevenness) in an output plane occurs. For this reason, if a sampling area is not sufficiently large, since an original document that should be inhibited copying cannot be recognized, the job-lock function does not operate, resulting in high possibility of occurrence of a security hole.